Nephropathy is a disease that typically develops over a prolonged period (e.g., 10-15 years) during which time the ability of the kidneys to properly function diminishes. Once the disease has progressed to end-stage renal disease (ESRD), a kidney transplant or dialysis may be the only treatment option. The disease is caused, for example, by immune disorders (e.g. IgA nephropathy) or diabetes (e.g. diabetic nephropathy). In either case, nephropathy is characterized by the trapping of protein deposits, such as, the protein immunoglobulin A (IgA), inside glomerular capillaries of the kidney. These glomerular capillaries serve as the kidney's filtration system to filter waste and water from the blood. The protein deposits prevent the glomerular capillaries from properly filtering the blood resulting in high protein levels in the urine.
Once the glomerular capillaries are damaged, they cannot be repaired. Thus, treatment of nephropathy typically involves slowing the progression of the disease rather than curing it. Treatment may consist of, for example, administration of therapeutics, such as angiotensin converting enzyme (ACE) inhibitors which reduce urine protein levels. A solution of the therapeutic may be delivered to the kidneys systemically. Systemic delivery, however, has several disadvantages. In particular, in systemic delivery techniques, the whole organism is treated therefore greater amounts of drugs must be supplied which are sometimes toxic to the organism.
Local delivery techniques may be used to overcome some of the disadvantages of systemic delivery techniques, however, a separate set of problems arise. Typically, in local delivery techniques the therapeutic is injected into a blood stream at a point upstream from the treatment site or into an unperfused vessel region after first occluding the vessel region to inhibit blood flow. In either case, due to the natural laminar flow profiles within the renal artery and kidney and reduced blood flow to diseased kidney regions, the blood flow may not evenly distribute the therapeutic to the desired treatment site.